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Updated: Aug 8, 2026
In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function
Published on: October 16, 2013
In vitro effect of interleukin-12 on antigen-specific lymphocyte proliferative responses from persons infected with
P Uherova1, E Connick, S MaWhinney
1Division of Infectious Diseases, University of Colorado Health Sciences Center, Denver 80262, USA.
Insights
Interleukin-12 (IL-12) boosts immune cell responses to common antigens in human immunodeficiency virus (HIV)-infected individuals with higher CD4 counts. This suggests IL-12 may help restore immune function in early-stage HIV infection.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Human immunodeficiency virus (HIV) infection leads to progressive depletion of CD4+ T lymphocytes, impairing immune function.
- Interleukin-12 (IL-12) is a cytokine crucial for cell-mediated immunity and T-cell activation.
- Understanding factors that modulate immune responses in HIV is critical for therapeutic development.
Purpose of the Study:
- To investigate the relationship between CD4+ lymphocyte count and the in vitro effect of IL-12 on lymphocyte proliferation.
- To assess IL-12's impact on responses to microbial recall antigens in HIV-infected individuals.
Main Methods:
- Peripheral blood mononuclear cells (PBMC) were isolated from 30 HIV-infected individuals and 10 seronegative controls.
- PBMC were stimulated with Candida, tetanus toxoid, and streptokinase antigens in the presence or absence of IL-12.
- Lymphocyte proliferative responses were measured, and limiting dilution analysis was performed.
Main Results:
- IL-12 significantly enhanced lymphocyte proliferation to microbial recall antigens in HIV-infected individuals with >200 CD4+ cells/mm³.
- The enhancing effect of IL-12 was most pronounced in individuals with CD4+ counts between 200-500 cells/mm³.
- IL-12 had minimal effect on PBMC from individuals with advanced HIV disease (lower CD4+ counts).
- Limiting dilution analysis indicated that IL-12 increased the number of antigen-responsive cells, not the proliferation extent.
Conclusions:
- IL-12 can restore antigen-specific lymphocyte proliferation in HIV-infected individuals with preserved CD4+ T-cell counts.
- The efficacy of IL-12 is dependent on the CD4+ lymphocyte count, suggesting a potential therapeutic window.
- IL-12 acts by increasing the number of responding lymphocytes, highlighting its role in immune reconstitution.
Abstract:
The relationship between CD4 lymphocyte count and the in vitro effect of interleukin (IL)-12 on lymphocyte proliferative responses to Candida, tetanus toxoid, and streptokinase antigens was studied in peripheral blood mononuclear cells (PBMC from 30 human immunodeficiency virus (HIV)-infected persons and 10 seronegative controls. IL-12 significantly increased proliferative responses to microbial recall antigens of PBMC from HIV-infected persons with >200 CD4 lymphocytes/mm3 but had little effect on PBMC from patients with more advanced disease. The greatest increase was seen in patients with 200-500 CD4 cells/mm3. Results of limiting dilution analysis suggested that the increase in antigen-specific lymphocyte proliferation in the presence of IL-12 was due to an increase in the number of responding cells rather than an increase in the extent of proliferation of a fixed number of responder cells.
